Add linting CI for the frontend

.github/workflows/frontend.yml

@@ -13,6 +13,27 @@ on:
     branches: [ 'main' ]
 permissions: read-all
 jobs:
+  lint:
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: 'frontend'
+    steps:
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8
+
+      - name: Set up Node.js
+        uses: actions/setup-node@395ad3262231945c25e8478fd5baf05154b1d79f
+        with:
+          node-version: "24"
+          cache: "npm"
+          cache-dependency-path: '**/package-lock.json'
+
+      - name: Install dependencies
+        run: npm ci --legacy-peer-deps
+
+      - name: Run ESLint
+        run: npm run lint
+
   build:
     runs-on: ubuntu-latest
     defaults:

frontend/eslint.config.mjs

@@ -0,0 +1,18 @@
+import { defineConfig, globalIgnores } from "eslint/config";
+import nextVitals from "eslint-config-next/core-web-vitals";
+import nextTs from "eslint-config-next/typescript";
+
+const eslintConfig = defineConfig([
+  ...nextVitals,
+  ...nextTs,
+  // Override default ignores of eslint-config-next.
+  globalIgnores([
+    // Default ignores of eslint-config-next:
+    ".next/**",
+    "out/**",
+    "build/**",
+    "next-env.d.ts",
+  ]),
+]);
+
+export default eslintConfig;